Question

Describe the chain of events that occur if oxygen is deprived from a cell or individual, i.e. why will you die if you do not get oxygen to your cells? Go step by step, describe the effect on the ETS and chemiosmotic phosphorylation, the Kerbs cycle, the conversation of pyruvate to acetyl CoA, and glycolysis.

Answer 1

I will glaze over the reason with you but you can go in much more detail than I'm about to

Oxygen plays an important role in the electron transport chain as it is the final acceptor of electrons, without reduction of O2 the chain cannot function, no protons can be pumped across the inner mitochondrial membrane. Infact ATP synthase will actually start running in reverse (but there are proteins that prevent this from occurring).

Thus, the electron transport chain shuts off, cells have a limited ability to produce ATP. This leads to the shut down of the TCA cycle likely due to the build of reduced electron transporters (NADH, FADH2, ETC)

Now lets talk about glycolysis, essentially glycolysis branches off to a bunch of different pathways (pentose phosphate pathway, krebs cycle, fermentation, etc). It produces ATP but if you look at the path way you should notice that it requires the reduction of NAD+ to NADH. This is a major problem, because since the electron transport system is shut down the cell has a limited ability to oxidize NADH to NAD+. So what keeps the Glycolysis running and ATP production going, FERMENTATION! An enzyme called lactate dehydrogenase, by converting pyruvate to lactic acid NADH can be oxidized to NAD+ and glycloysis can continue!

The main problem with this though being the build up of lactic acid in the cell which can have very damaging effects (for proper cellular function at least in humans you need a pH around 7.4). In humans and most animals this lactic acid is excreted from the cells, where it is transported to the liver, but you can look up the (Cori cycle) if you are interested.

The liver can only take so much of this lactic acid though and many other processes will be completely messed up due to this loss of ATP production.

I hope this was helpful the best way to learn this stuff is just to learn the pathways.